Moral philosophers sometimes talk about what is known as the 'wisdom of repugnance' or the 'yuck factor'. Few ethicists subscribe exclusively to the idea, but a small number hold that true morality is a matter of what we find disgusting or not disgusting. In the context of people's reactions to aborted foetuses being incinerated to heat hospitals, we might agree that disgust plays a major role in our initial reaction and thoughts on the issue. But should we always trust our instinctive moral reaction?

In 2001, work by social psychologist Professor Jonathan Haidt of New York University had some startling results when he went about asking this exact question. Participants were told to reflect on the morality of incest. Naturally, when asked, almost everyone said they thought incest was immoral. Then, more information about the scenario was given. Participants were told that the brother and sister were fully-mature, single adults who would use contraception, thereby avoiding genetic problems in offspring. Further, both fully consented and there was no inequality of power in the relationship. The brother and sister also claimed to enjoy the experience and no-one would ever know about it, so it would not affect their other relationships. Participants were again asked if they thought this scenario of incest was wrong. For the most part, very few people changed their minds. When asked why, they could give no substantial answers other than "it just is."

Professor Haidt calls this phenomenon "post-hoc rationalisation." We have an immediate disgust reaction to something, like incest, and we then work backwards to rationalise our view that it is morally wrong. Relying purely on these evolved instincts, however, may not necessarily lead to moral truth; that by accident of nature we have evolved to find, for example, incest disgusting due to it leading to offspring which are less likely to survive, is not necessarily logically or ethically meaningful when considering the morality of incest. Could the same be true for the burning of foetuses to warm a hospital?

It seems natural for us to feel somewhat attached to an aborted foetus (or 'baby', as some may prefer to call it). It doesn't hold the same emotional or psychological significance as an arm or leg. Should this change how we treat the aborted foetus compared to other waste tissue? Certainly - as it is likely that what is done with the foetal remains will have a significant impact on the psychological wellbeing of the woman who had the abortion. But let's say that she, for whatever reason, wanted the foetus to have some sort of practical meaning for the world. She might request that the remains be buried under a tree, so that the biological material degrades and is absorbed by another organism, another life form. In this sense, the foetus' 'life' wasn't all for nothing. But what is so different between that and wishing for the foetus to be incinerated with other biological material to generate heat which will then give physical warmth and comfort to people in a hospital? If the woman definitely wishes for this to happen, and is fully aware of what this means, who are you or I to say that she can't be afforded her own chance of reconciliation and closure?

Some might say that it is the nature of incineration, the idea of it being burned. Unless you take religious issue with cremation also, what is the salient difference? It can only be said that it is the technical nature of the burning and what one gains at the end of that process that bears any dissimilarity. In one scenario we waste energy in the form of heat to end up with a pile of ashes, and in the other scenario we gain energy in the form of heat and end up with living people receiving a short respite from the cold. The major point of distinction, then, is what we end up with: do we prefer an urn of ashes or the knowledge that energy (in the form of heat) was passed on to other life forms? While you might feel slightly uncomfortable about one of these options, who's to say that both aren't meaningful in their own ways? In fact, there's almost something spiritual about the idea of passing on energy to other life forms, to other people.

I'd therefore urge people like the health minister, Dr Dan Poulter, to think more deeply about this issue. It might be that you reach a different moral conclusion to the one I've described here. However, wherever your ethical reasoning takes you, I hope you will be able to avoid a post-hoc rationalisation.